Building SQL QueriesDocumentation

SQLite

The @databases/sqlite library provides a safe and convenient API for querying SQLite databases in node.js.

N.B. you should only have one process connected to a given SQLite database at a time.

Usage

import connect, {sql} from '@databases/sqlite';
// or in CommonJS:
// const connect = require('@databases/sqlite');
// const {sql} = require('@databases/sqlite');

const db = connect();

db.query(sql`SELECT * FROM users;`).then(
  results => console.log(results),
  err => console.error(err),
);

For details on how to build queries, see Building SQL Queries

API

connect(fileName)

Create a database connection for a given database. You should only create one connection per database for your entire applicaiton. Normally this means having one module that creates and exports the connection pool.

In memory:

import connect from '@databases/websql';
const db = connect();

File system:

import connect from '@databases/websql';
const db = connect(FILE_NAME);

The Database inherits from DatabaseTransaction, so you call Database.query directly instead of having to create a transaction for every query. Since SQLite has very limited support for actual transactions, we only support running one transaction at a time, but multiple queries can be run in parallel. You should therefore only use transactions when you actually need them.

Connection.query(SQLQuery): Promise<any[]>

Run an SQL Query and get a promise for an array of results.

Connection.queryStream(SQLQuery): AsyncIterable<any>

Run an SQL Query and get an async iterable of the results. e.g.

for await (const record of db.queryStream(sql`SELECT * FROM massive_table`)) {
  console.log(result);
}

Connection.tx(fn): Promise<T>

Executes a callback function as a transaction, with automatically managed connection.

When invoked on the ConnectionPool object, the method allocates the Connection from the pool, executes the callback, and once finished - releases the connection back to the pool. However, when invoked inside another task or transaction, the method reuses the parent Connection.

A transaction wraps a regular task with additional queries:

  1. it executes BEGIN just before invoking the callback function

  2. it executes COMMIT, if the callback didn't throw any error or return a rejected promise

  3. it executes ROLLBACK, if the callback did throw an error or return a rejected promise

const result = await db.tx(async transaction => {
  const resultA = await transaction.query(sql`SELECT 1 + 1 AS a`);
  const resultB = await transaction.query(sql`SELECT 1 + 1 AS b`);
  return resultA[0].a + resultB[0].b;
});
// => 4

ConnectionPool.dispose(): Promise<void>

Dispose the connection pool. Once this is called, any subsequent queries will fail.

Transaction
Testing